Temporary thread protector



Feb. 25, 1958 R. E. GROH ET AL 2,824,579

TEMPORARY THREAD PROTECTOR Filed April 11, 1955 RICHARD aeaou INVENTORS JOHN c MAY zli'oltam A TTORNEYS United States Patent TEMPORARY THREAD PROTECTOR Richard E. Groh and John C. May, Ojai, Calif.

Application April 11, 1955, Serial No. 500,372

2 Claims. (Cl. 138-96) This invention relates to devices for protecting pipe threads and more particularly, to a temporary protector which may be quickly attached and detached from the threaded end of a pipe.

While there are numerous applications for the present invention, its preferred use is with oil well casing pipe, and for purposes of the present specification, the invention will be described in this connection.

Usually, casing pipe for lining an oil well bore hole is supplied in sections approximately thirty feet long and ranging in diameter from three to fifteen inches. One end of each section is diametrically tapered and externally threaded. The other end is provided with internal matching threads. In setting the casing, a first section is elevated by means of the derrick traveling block and lowered into the bore hole until only two or three feet remain above the rotary table. This section is locked in place and the traveling derrick block is disconnected and used to elevate a second section into a vertical position above the first section. The two sections are then screwed together and lowered into the bore hole until only a few feet of the free end of the second section is exposed. A third section is then picked up by the traveling block and the process repeated.

The casing pipe sections generally number in the hundreds and are conventionally stacked in a horizontal position close to the derrick so that individual sections may be connected to the traveling block for transferral into position to be joined to the previous section, as described above.

It is important that the threads on the casing pipe sections be clean and undamaged at the time they are to be attached. In order to insure this protection, they are customarily supplied with permanent type thread pr0tec tors in the form of short cylindrical collars threaded over the exposed externally threaded ends of the pipes. These collars remain on the pipe sections until a day or so before the casing setting operation is to take place. They are then all removed by unscrewing the same and the threads wiped clean and inspected. The reason for removing these protecting collars prior to the casing setting operation rather than during the operation, is to save time. It would take far too long to set casing if the operator had to unscrew the protecting collar and clean the threads of a pipe section while the section was being held in suspended position by the derrick just prior to screwing to the previous section. It is far preferable to clean and inspect these threads a day or two before the operation when there is ample time available and during which time the traveling block may be used for other purposes.

It is very important however, that the casing pipe threads be protected between the time the protecting collars are removed and the time the pipe section is actually carried into position for connection to the previous sec tion, particularly since one end of the casing pipe drags along the ground or derrick floor as its other end is being lifted by the traveling block.

r' 2,824,579 Patented Feb. 1958 Accordingly there has been developed a temporary thread protector in the form of a cylindrical collar of larger diameter than the casing pipe, which may be quickly placed over the threaded end of the pipe and secured in position, and then subsequently relatively quickly removed just prior to the screwing of the pipe section to the previous section.

- One such type of prior art temporary thread protecting collar, for example, includes an internal annular rubber tube which may be inflated after the collar has been placed over the threads to protect the same and temporarily hold the collar in place. The collar may then be easily removed by simply deflating the tube. Another present day type includes annular wedge elements mechanically levered into tight engagement with the thread after the supporting collar has been placed in position.

Both of the above types of thread protectors are relatively expensive and complicated to operate. Further, thread protectors of the binding wedgetype can result in damage to the threads on the casing pipe if too much wedging force is applied.

It is a primary object of the present invention accordingly to provide a vastly improved temporary thread pro tector which is not only extremely simple to operate, but is considerably less expensive to manufacture and which therefore results in an overall saving in a casing setting operation.

More particularly, it is an object to provide a temporary thread protector for oil well casing pipe sections which is rugged, employs only one major moving part, and which will not damage the casing pipe threads to which it is temporarily affixed.

These and other objects and advantages of the present invention are achieved by employing a split collar which may be manufactured directly from one of the permanent collars initially supplied with the pipe casing. The slit permits the collar to be circumferentially expanded or contracted over a given range whereby the collar may be quickly placed over the threaded end of a casing pipe section. A single slide plate is mounted on the collar adjacent the slot. Cooperating cam means on the plate and adjacent the slot are arranged so that sliding movement of the plate will circumferentally contract the collar about the threaded pipe end.

The interior of the split collar is partially threaded so that upon contraction of the collar, these threads will engage the pipe threads and serve the double function of securing the collar in position and protecting the pipe threads. Cross-threading is avoided by making the internal collar threads in circumferential sections.

A better understanding of the invention will be had by referring to the preferred embodiment shown in the the accompanying drawings, in which:

Fig. 1 is a perspective view of a conventional casing pipe section and permanent type protecting collar;

Fig. 2 is a perspective view of the temporary thread protector of the present invention prior to positioning on the threaded end of a casing pipe section;

Fig. 3 is a cross-section taken in the direction of the arrows 3-3 of Fig. 2;

Fig. 4 is another perspective view of the temporary thread protector of Fig. 2 in contracted or lockedposition;

Fig. 5 is a cross-section taken in the direction of the arrows 55 of Fig. 4; and,

Fig. 6 is a perspective view showing how the thread protector is secured over the threaded end of the casing pipe of Fig. 1.

Referring to Fig. 1, there is shown a section of casing pipe 10 having an externally threaded end 11 for threadedly receiving a conventional permanent type protecting collar 12. The collar 12 is internally threaded as at 13. Only a few threads in exaggerated size have been shown in Fig. 1. Normally, these threads are of very small pitch and many in number so that the unscrewing of the 'collar 12 is ordinarily a time consuming operation.

As explained previously, time is saved by removing all of the protecting type collars 12 a day or two before a casing setting operation is to take place. The threaded pipe ends may then be cleaned and inspected and a temporary type thread protector placed in position over the threads.

One embodiment of such temporary thread protector constructed in accordance with the present invention is shown in perspective view in Fig. 2, as comprising a cylindrical collar 14 having a lateral slit 15 to provide a split collar. Collar 14 may be manufactured directly from the permanent type collar 12 of Fig. l by simply cutting down one lateral side.

A slide plate member 16 provided with a pair of angulated cam slots 17 and 13, is slidably mounted to the collar 14 by flanges 19 and 20 disposed on either side of the slit 15. These flanges are turned inwardly towards the slit to provide portions adapted to overlie the side edges of the slide plate 16 and thus provide a guiding channel for the plate. The flanges 19 and 2t may be welded or otherwise permanently secured directly to the collar 14.

As shown more clearly in Figs. 2 and 3, .a metal wrap 21 surrounds the collar 14 and is rigidly secured to the rear portion of the collar as by welding. One front end edge 22 overlies the slide plate 16, while the other front end edge 23 of the wrapping overlaps the front end 22 as shown. While the Wrapping 21 is integral with the collar about a major circumferential portion thereof, the wrapping portion overlying the slide plate is separated from the collar slit portion between the collar flanges 19 and 20. By this construction, when the collar 14 is circumferentially contracted, the front end edge 22 is moved further under the overlapping end edge 23. Preferably, the overlapping wrapper end 23 is provided with integral guide pins 24 and 25 projecting inwardly through slotted recesses 26 and 27 respectively in the wrapper end 22. The overlapping end portions of the wrapper are thus guided during relative sliding movement and the portion of the wrapper 21 overlying the slide plate 16 serves as a further guide and protector for the plate.

The slide plate 16 is used to com together the collar edges defining the slit 15 in order to circumferentially contract the collar 14 after it had been placed about the threaded end of the pipe casing. This camming action is achieved by cam members in the form of pins 28, 25 and 31 projecting through the angulated cam slots 17 and 18 as shown in Figures 2 and 3. Two of these pins, 28 and 29 as best seen in Figure 3 are rigidly secured to the underside of the overlying portion of the wrapper 2%. Since this wrapper is rigidly secured to the collar flange 19 as viewed in Fig. 3, these cam members are rigid with respect to the collar side above the slit. As shown, they project down from the underside of the wrapper through the cam slot 17 of the slide plate 16 and serve to limit the longitudinal sliding movement of the plate.

The other two cam members 30 and 31 aresecured directly to the collar adjacent the slit 15 and project upwardly through the angulated cam slot 18 of the slide plate. Referring once again to Fig. 2, one edge of the angulated slot 18 is provided with spaced recessed portions 32 and 33 adapted to receive the cam members 30 and 31 respectively, when the slide plate 16 is moved to the right.

In order to move the slide plate 16 from the position shown in Figs. 2 and 3 to the position shown in Figs. 4 and 5, a simple hand lever is employed. Referring to Fig. 6, a small bore 34 in the end of the slide plate 16 is adapted to receive a hook'35 on the end ofa lever bar 4 36. A pair of arms 37 and 38 are pivoted to the level bar at 39 relatively close to the book 35. The frcc ends of the arms 37 and 38 terminate in hooks 40 and 41, respectively, which are adapted to engage about the circurnferential edge of the split collar 14. The arms are constructed to diverge from the pivot point 39 to pass on either side of the slide plate 16 so as not to interfere with movement thereof.

With the above described arrangement, movement of the lever bar 36 away from the operator as indicated by the arrow A, will urge the slide plate 15 from the posi tion shown in Fig. 2 to the position shown in Fig. 4. As shown in Fig. 4, the base end edge 42 of the slide plate will then project beyond the end of the split collar and by simply tapping this base end with a mallet, the slide plate may be returned to its initial position as shown in Pig. 2.

The operation of the temporary thread protector will be evident from the above description. Normally the split collar 14 is biased to a circumferentially expanded position so that the slide plate is initially in the position of Fig. 2. Further expansion of the split collar is prevented by the guide pins 24 and 25 in the overlapping ends of the wrapping ends of the wrapping 21, as well as by the cam members 29 and 31 disposed at the ends of the cam slots 17 and 18 respectively. In its expanded position, the split collar may easily be inserted over the threaded end of a casing pipe section such as the pipe section 10 of Fig. 1 or pipe section shown in Fig. 6.

With the split collar in position, the lever bar 36 is employed to force the plate 16 under the overlying wrapping 21. The cam members 30 and 31 will then be cammed by the edge of the cam slot 18 towards the cam members 28 and 29 to circumferentially contract the split collar. When the slide plate is urged sulilciently far under the wrapping 21, the cam members 30 and 31 will engage the recessed edge portions 32 and 33 of the cam slot respectively and thus secure the plate in its inward position as clearly shown in Fig. 4.

Circumferential contraction of the split collar will cause the collar to securely engage the exposed threads on the casing pipe. It will be noted in Figs. 3, 5, and 6 that interior threads 43 have been provided in the split collar. These threads extend only for given circumferential distances whereby smooth unthreadcd spaces 44 are present. By providing internal threads in circumferential sections in this manner, these sections of threading may more easily be positioned to interengage with the exterior threads on the casing pipe and there will be substantially no possibility of cross-threading. The interengagement of the threaded portions will not only secure the collar in place, but will also distribute the engaging pressure over a relatively large area of the external threads of the casing pipe.

With the temporary thread protector in place, the threads of the casing pipe are protected while its other end is picked up by the traveling block for securing the pipe section to the previous casing pipe section during a casing setting operation. Just prior to connecting the two sections, the temporary protector is readily removed by simply tapping the base end 42 of the slide plate 16 with a mallet to knock the plate cam slot recesses 32 and 33 from under the cam members 30 and 31. Since the split collar is biased to its expanded position, the plate 16 will then be cammed to its outer position shown in Fig. 2 and the collar easily removed.

By employing two cam members 28 and 29 in alincmcnt with the split collar slit 15, the contracting camming pressure exerted by the plate 16 upon inward movement, will be relatively uniform so that the split collar will be evenly circumferentially contracted. The actual distance the edges of the slit 15 move together upon contraction of the collar as depicted in Figs. 3 and 5 is relatively small. The distance between the guiding flanges 19 and 20 and edges of the slide plate is made sutiicinet to accommodate this small movement and still permit the flanges to overlie the slide plate edges when the collar is in expanded position.

From the above detailed description, it will be seen that the present invention provides a mechanically simple and rugged temporary thread protector. In the event the permanent type collars 12 are used for manufacturing the thread protector, the inner threads may be milled out in sections to provide the circumferentially spaced threads desirable in the present invention.

Since the device employs essentially only one moving part, in the form of the slide plate 16, it is very economical to manufacture and extremely simple to operate.

Modifications in the specific structure falling within the scope and spirit of the present invention will occur to those skilled in the art. The device is therefore not meant to be limited to the specfic embodiment described and shown in the accompanying drawings.

What is claimed is:

1. A thread protector comprising: a cylindrical collar having a lateral slit extending longitudinaly through said collar whereby said collar is circumferentially contractable; a slide plate dimensioned to cover said slit, and positioned to slide substantially parallel to said slit; guiding flanges secured to said collar adjacent each side of the collar edges defining said slit respectively and extending substantially parallel to said slit, said flanges turning in wardly towards said slit to provide portions adapted to overlie opposite longitudinal edges of said slide plate to provide a guiding channel for said slide plate; and cam members secured with respect to said collar adjacent opposite side edges of said collar defining said slit, said slide plate including slots adapted to receive said cam members, said slots being elongated and angulated with respect to each other, whereby movement of said slide plate cams said cam members towards each other to circumferentially contract said collar.

2. A thread protector according to claim 1, in which said cylindrical collar is provided with internal circumferentially spaced threads, the spacing between said spaced threads being relatively smooth whereby circumferential contraction of said collar about external threads results in substantially no cross-threading between said internal threads and said external threads.

References Cited in the file of this patent UNITED STATES PATENTS 1,000,375 Cable Aug. 15, 1911 1,295,776 McClelland Feb. 25, 1919 2,073,389 Engstrom Mar. 9, 1937 2,692,417 Primick Oct. 26, 1954 

